Tony D Posted January 23, 2009 Share Posted January 23, 2009 Rather than restricting port size arbitrarily (That is, symmetrically), I'd say bring the bottom of the port UP with a filler like Devcon, this increases the shortside radius enhancing flow. The reduced port sizing will increase velocity, the larger radius on the short-side increases flow...add a very light bit of bowl work to really take advantage of the increased velocity...and I think you may be surprised by how much it picks up on the bottom end, with even a nice bump over stock on the top end. I don't think the smaller ports per se will 'restrict' or 'strangle' an otherwise 'stock' engine. There is porting that can be done to increase flow on the bottom end---it's just usually focused on the top end of the RPM range. Because it takes rpms to get it to the velocity it needs to be at to do the things it does... Pontiac is going under with 'wider is better' right? I always liked smaller holes, personally. They just look cleaner all around. Baaaaaaa! Quote Link to comment Share on other sites More sharing options...
ozconnection Posted January 23, 2009 Author Share Posted January 23, 2009 The idea behind using devcon on the ports is an interesting one but I don't see it as particularly straightforward. Reshaping the ports in this way and I'm assuming you mean the currently installed N42, would preclude the whole 'simple' exercise. If I had lots of money and time to develop this concept, I'm sure I would achieve an excellent result but since I have neither in great quantities, I would have to opt for the 'simpler' and 'cheaper' option of just swapping heads. Thanks anyway Tony, your inputs have been noteworthy. Cheers. Smaller holes..............naughty boy. Quote Link to comment Share on other sites More sharing options...
Daeron Posted January 24, 2009 Share Posted January 24, 2009 hey, the smaller holes net you more torque "down low" Quote Link to comment Share on other sites More sharing options...
Tony D Posted January 24, 2009 Share Posted January 24, 2009 Daeron is on the downlow? Whatsay? Huh? ... Quote Link to comment Share on other sites More sharing options...
ozconnection Posted January 24, 2009 Author Share Posted January 24, 2009 You killed it. Quote Link to comment Share on other sites More sharing options...
ozconnection Posted January 25, 2009 Author Share Posted January 25, 2009 A couple of piccy's, as promised. Nice stock chamber shape, what do you think? Quote Link to comment Share on other sites More sharing options...
Tony D Posted January 27, 2009 Share Posted January 27, 2009 I saw someone who had that head in a Maxima...caught the casting number out of the corner of my eye passing through the breakers one day... went "Huh?" That's and L20A Casting... Went back, sure enough, someone had put an L20A replacement Japanese engine in a later Maxima WAGON. I wonder how they liked that smaller engine in that larger car...in SoCal? Heh heh heh... Quote Link to comment Share on other sites More sharing options...
ozconnection Posted January 28, 2009 Author Share Posted January 28, 2009 I wonder how they liked that smaller engine in that larger car...in SoCal? Heh heh heh... Heh Heh, I know what it's like to drive with an L20A, decompressed for turbo, without the turbo! The funny thing is, in Japan most of them run the smaller engines anyway from what I've seen!! Add air, steer and an auto trans and WTF!! "I hope you're not in a hurry" Quote Link to comment Share on other sites More sharing options...
blue72 Posted January 30, 2009 Share Posted January 30, 2009 I saw someone who had that head in a Maxima...caught the casting number out of the corner of my eye passing through the breakers one day... went "Huh?" That's and L20A Casting... Okay, that makes more sense. I had seen you tell this story in another thread, but you said it was a Y20 head. I assumed you meant Y70 because I had never found any other mention of a Y20:confused:. ozconnection, do you know if the early L20ET manifold has notches on the bottom of the runners to match those on the head? Quote Link to comment Share on other sites More sharing options...
ozconnection Posted January 30, 2009 Author Share Posted January 30, 2009 ozconnection, do you know if the early L20ET manifold has notches on the bottom of the runners to match those on the head? It's been a long time since I've had these manifolds. I sold them to guys who wanted them for their L28 turbo buildups here in Oz. From memory, I think not. Don't quote me, though! Quote Link to comment Share on other sites More sharing options...
kolonelklink87 Posted February 23, 2009 Share Posted February 23, 2009 I have a friend who fits this description perfectly. She FREAKS when I drive her Z. I get the idea of the thread, I just thought maybe a dissenting opinion was in order. Choking down an L6 is in my estimation counterproductive, and as you point out, there are other ways to change the powerband without having to resort to smaller than usual ports. It's interesting to see how much resistance there is to this concept amongst some of the z-drivers where the standard mentality is "bigger ports=better". Aside from the obvious oversimplification in that scenario it is important to remember that ozconnection (and myself) aren't driving z's, we drive c's (cedrics, 240c, 260c, 280c, and in the 330 body code also gloria). Compared to the nimble Z's with a tare weight of say 1067-1200kg, the cedrics are the lumbering brontosaurus of the nissan Lseries equiped vehicles(excepting the patrol of course) with a tare weight closer to 1500kg. Consider trying to drag your race-ported Z whilst bearing the burden of an entire seized motor in the boot(trunk) and you'll have some concept of the challenges of such a build. In this scenario Torque is king. Beleive me, my 260c coupe was ported & cammed before it got to me and im strongly considering pulling this "performance" head for something narrower. To the Z-driver the fact that their engines don't kick in until well beyond 3000rpm is water off a ducks back but if you're running this style of engine in a luxo-saloon, getting off the mark without changing your clutch twice a week can be a mite troublesome. The obvious response will of course be "why dont you get a Z then?" the response is simple; why to Z drivers spend ridiculous amounts of time and money on beefing up and antequated Lseries when they could get the same results from a modern transplant and a cheap turbo? -nostalgia, pride, stubborness and passion. Certainly for a daily driver this is a well-notable direction to hold on to the heritage of the vehicle yet still maintain the capability to express your engines "power" without looking like a manic jockey flailing his screaming horse unsympathetically through first and second gears. The horse will probably love you longer for not revving the guts out fo it too... Perhaps some of the Z-drivers should consider a page from the cedric book? Food for thought... Quote Link to comment Share on other sites More sharing options...
kiwi303 Posted February 23, 2009 Share Posted February 23, 2009 I had an 83 Laurel Medallist. & series BMW competitor, electric everything, heavy as sin, and with loads of options. It could beat many lighter cars off the lights with it's piddly little L20E engine, but would fall flat by the time it finished crossing the intersection. Gobs of pulling power at low revs on the motorway tho, cruise control up the bombay hills at 100Km/H when many other cars would be dropping speed down to 90 or 80. The L20 6cyl is actually an underrated engine IMO. Quote Link to comment Share on other sites More sharing options...
stagefumer11 Posted March 1, 2009 Share Posted March 1, 2009 Kiwi303, Agreed. ! I loved my L20et also, got 200rwhp out of her. Actaully the bombay hills is the best long load tester hill in new zealand.! Quote Link to comment Share on other sites More sharing options...
JMortensen Posted March 1, 2009 Share Posted March 1, 2009 In the US we had L24E Maximas. I've never heard anyone complain that the ports were too large. Feel free to disagree, but I still think you guys are headed backwards. If you check zhome.com and look at the reported dyno results and particularly Keith Thomas's ITS results with different bolt ons, you'll see that at 2000 rpm an ITS engine which is as tweaked for high rpm hp as you can get while retaining the stock cam, intake, etc still shows 100 ft/lbs of torque at the wheels, when the engine only has a maximum of 120 at any point in the powerband. I'm betting it has pretty good torque right off idle, but it doesn't make sense to dyno a race engine there so I guess I can't prove it. Regardless, I think your scenario where the normal (still SMALL) ported head doesn't have any power until 3000 rpm is shown to be untrue. But regardless, I hope you do what makes you happy and enjoy the engine that you build. Quote Link to comment Share on other sites More sharing options...
ozconnection Posted March 2, 2009 Author Share Posted March 2, 2009 In the US we had L24E Maximas. I've never heard anyone complain that the ports were too large. Feel free to disagree, but I still think you guys are headed backwards. If you check zhome.com and look at the reported dyno results and particularly Keith Thomas's ITS results with different bolt ons, you'll see that at 2000 rpm an ITS engine which is as tweaked for high rpm hp as you can get while retaining the stock cam, intake, etc still shows 100 ft/lbs of torque at the wheels, when the engine only has a maximum of 120 at any point in the powerband. I'm betting it has pretty good torque right off idle, but it doesn't make sense to dyno a race engine there so I guess I can't prove it. Regardless, I think your scenario where the normal (still SMALL) ported head doesn't have any power until 3000 rpm is shown to be untrue. But regardless, I hope you do what makes you happy and enjoy the engine that you build. I think it's because you guys never had easy access to these small port heads, it was never really considered to be an option by engine builders. Head developers decided that it was easier to make a hole larger than smaller, flow gains confirmed by flow testing. It was decided that this was the right direction to take. And since these heads were built to be used by racers and the top end power was there, the street guys figured that big port heads were the shortcut to greater power as well. When we study the engines from some other makes, like the Ford Cleveland engines, the large port 4V heads had ports so large, they were essentially deemed useless even in racing circles. No port gas speed!!! Racers then opted for the smaller 2V heads, which had smaller ports and flowed less air (verified by the flow bench during testing and development) but these smaller heads comprehensively smacked the cars equiped with the 'better flowing' 4V headed engines. Even the aftermarket realized this and sold port tongues or fillers for those guys who ran 4V heads and wanted better engine response to match the 2V boys. Hmmmm, can we try some small port heads on our engines? This is exactly what I'm proposing. If there is a limit to top end power due to the small ports, a 'bigger' camshaft should fix that, shouldn't it? What about port gas speed? It should be there, all the way down to the bottom of the rev range, not just limited to the top rpms. And the way I see it, make the port too large and the port velocity through the head may never reach optimal speed until you're bouncing off 8K rpm (if even then). Just ask the Ford boys!! Cheers. Quote Link to comment Share on other sites More sharing options...
kolonelklink87 Posted March 2, 2009 Share Posted March 2, 2009 ...Regardless, I think your scenario where the normal (still SMALL) ported head doesn't have any power until 3000 rpm is shown to be untrue. But regardless, I hope you do what makes you happy and enjoy the engine that you build. I think you were referring to my post? If so I was expressing my frustration with my ported and cammed l26 w/e88 head (don't know the equivlent year for e88's from k330's in US zeds, ozconnection might know). I can't help but again stress the weight factor here, if you have low torque, low power before 3k(hell, 2500 if you will) in a zed you don't give a hoot because it doesn't affect your drivability. You don't need the extra pull to go for a casual cruise down to the shops for some milk and bread- your weight is down so you can do without it and still keep the revs down. In a "Ced" you're gonna have to hit the power range of the engine to avoid the yuppie sheila in the toyota yaris behind you beeping her well-bred little heart out at the lights. there's no doubt that the stock engine is capable of pulling that weight but there's always room for improvement. Going in a ported direction means you have to spend even more time at higher RPM - & when pull is compulsory this is going to seriously affect the longevity of your engine, in the C' you dont have a choice on this issue so you spend a very considerable amount of time in the powerband of the engine (compared to a zed where upping the rev's is an option for attracting attention and squashing beautiful passengers with g-forces). There was a very nice writeup elsewhere on hybrids regarding low-boost high-flow engines on the concept of flow. The points on that article were all very relevant and valid but the above are two points which are often overlooked due to the versatility of the z-chassis. This thread is about building an engine to suit a specific vehicle and intention, not an engine for your vehicle Having had the opportunity to drive ozcon's stock-port 280c w/holley I can tell you that car pulls- esp. compared to my MS'd & ported version (which has 0.2l less but also lighter being a coupe with many accessories stripped out). I'm very much looking forward to the chance to try a run with the new port and carb adjustments. Quote Link to comment Share on other sites More sharing options...
kolonelklink87 Posted March 14, 2009 Share Posted March 14, 2009 Here is a possible reason why you might want to go down this route...(though, i concede, in this instance it's a bit of a self-fulfilling prophecy). Thats ozcon's l28(NA!) pulling a JDM cedric and trailer with a combined weight exceeding 2000kg... not bad if you ask me. We took it on the freeway up to 100km/h, uphill, downhill, left right center... no issues. This thing is HEAVY. so many memories... (mmm... cedric convoy) Quote Link to comment Share on other sites More sharing options...
ozconnection Posted March 14, 2009 Author Share Posted March 14, 2009 I guess this illustrates the versatility of the L Series engine nicely. The Cedric may not be a fast car because of body weight and engine specification. The camshaft profile may limit how quickly the engine accelerates to redline but it's the same camshaft that allows this sort of towing capability to take place. You should 'feel' how toey the car is now since towing that lot. Feels like a rocket ship The L20A head has been reworked and I'll be picking it up on Monday. Some pictures to follow soon. Cheers. Quote Link to comment Share on other sites More sharing options...
HowlerMonkey Posted March 15, 2009 Share Posted March 15, 2009 Sweet........I towed a first generation maxima with a 280zx. Quote Link to comment Share on other sites More sharing options...
Tony D Posted March 15, 2009 Share Posted March 15, 2009 I puked squid tentacles, baby octapus, and raw fish out the right rear window of a car that looked exactly like the cream coloured one with the trailer attached! That car had an L28 with Triples and a Five Speed conversion eventually...yeah, it burned up clutches something fierce when you tried to drag race it. I think there is a reason the saloons got totally different intake manifolds later in the production run---the standard manifold just wasn't cutting it. And in each instance, the runners went smaller, not larger. It was for the application as those manifolds never appeared in any Z-Car from the factory. Only the heavier bodied saloon cars and behemoths I used to call 'Japanese Impalas' That cream car have the rear seat radio option, where the back seat passengers could listen to a different station than those in the front? Talk about 'made for Taxi Service!' LOL Yeah, those are some memories there! Man that octopus was vile coming back out... Quote Link to comment Share on other sites More sharing options...
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